Fred, good question. It may partly be a function of soft wood. Not sure what wood yours is, but my Mustang is Poplar.
I think soft woods like Poplar absorb the blow, getting a ding very easily like styrofoam would...and instead of the paint cracking & flaking off immediately, the paint can sink into the soft wood and still adhere.
On the other hand, very hard wood resists the blow. It's as if the thin coat of brittle paint gets pinched between the blow and the hard wood. The brittle paint takes most of the force, cracking, chiping, and braking off.
Just a theory. We got a Materials Engineer in the house?
